High temperature plasma generator having means for providing current flow through plasma discharge



Nov. 14, 1967 K. D. DAVIS 3,353,061 HIGH TEMPERATURE PLASMA GENERATOR HAVING MEANS FOR PROVIDING CURRENT FLOW THROUGH PLASMA DISCHARGE Original Filed May 5, 1965 2 Sheets-Sheet 1.

' INVENTOR. KENNETH 0. DAVIS ATTORNEY Nov. 14, 1967 K. D. DAVIS 3,353,061

HIGH TEMPERATURE PLASMA GENERATOR HAVING MEANS FOR PROVIDING CURRENT FLOW THROUGH PLASMA DISCHARGE Onginal Filed May 5, 1965 2 Sheets-Sheet 2 \llllhllllllh INVENTOR. KENNETH D. DAVIS M 7 M-IJ ATTORNEY United States Patent HIGH TEMPERATURE PLASMA GENER- ATOR HAVING MEANS FOR PROVID- ING CURRENT FLOW THROUGH PLAS- MA DISCHARGE Kenneth D. Davis, 224 N. Xenophen St.,

Tulsa, Okla. 74127 Continuation of application Ser. No. 452,751, May 3, 1965. This application Apr. 10, 1967, Ser. No. 634,408 3 Claims. (Cl. 315-111) ABSTRACT OF THE DISCLOSURE An electrical device, namely an improved high temperature plasma generator including means for creating high velocity and high temperature plasma.

This application is a continuation of Ser. No. 452,751, filed May 3, 1965, now abandoned.

This invention relates to an improved method and apparatus for accelerating, stabilizing and increasing the temperature of ionized gas particles flowing from a plasma apparatus. This invention guides the flow of ionized particles in a straight concentrated flow to the surface cansing not only a more eflective stabilized concentration of plasma on a selected area but also exceedingly increased temperature in that area over that which normal plasma would deliver.

Plasma being a good conductor of electricity because of its ionization properties will also be influenced by a magnetic flux derived from setting up a magnetic field. For instance, referring to FIGURE 2 in a magnetic field, magnetic flux is set up in a direction perpendicular to the stream of plasma moving out of a plasma jet gun. The moving ionized particle stream experiences a magnetic force parallel to the moving stream. By varying the current at the rheostat, the force of accelerating action on the moving particles can be increased or decreased. Using the type of apparatus shown in FIGURE 2 eliminates a requirement for sealed bearings since there are no moving parts.

The patent to Giannini, 2,944,140, issued July 5, 1960 referring to column 1, lines 35-40, claims stabilization and concentration of the plasma flame in a plasma gun, but does not disclose apparatus which will produce a stabilized highly accelerated flame with increased temperatures. This improved plasma flame can be produced with the apparatus which I shall disclose. My new .invention is an improvement over the Giannini patent. While this patent provides a magnetic field for confining the plasma jet in a vortical pattern, my invention not only confines the plasma stream in a directed pattern, but by the addition of an additional electrical are in combination with an external magnetic field, I am not only able to add extreme stability to a plasma stream previously having irregular velocity, 'but with the aid of a strong magnetic field and the additional are, I am able to increase the temperature of the plasma jet stream to 20,000-30,000 F. and over. With the discovery of such high temperatures developed in the plasma stream using the disclosed apparatus, such materials as tungsten and other known refractories can be evaporated and mixed with many metas and ceramic compounds which heretofore laboratories have not been able to combine.

The plasma jet apparatus which I propose to disclose is constructed of steel and is provided with an arc chamber having a close fitting discharge nozzle. Into the cylindrical discharge nozzle is inserted a carbon or thoriated tungsten liner, in close proximity to the liner, which is 3,353,061 Patented Nov. 14, 1967 an electrode, is a second electrode made from carbon, graphite or thoriated tungsten. This rod which projects from the base of the metal apparatus is fitted with a clamp outside the metal body which in turn is connected to a source of direct current power. The are chamber itself is cooled by water which passes through a copper-lined jacket surrounding the chamber. The are chamber is also equipped with a perforated plate in the lower section for the passage of inert gas, such as helium or hydrogen. Inert gas under slight pressure passes through the arc chamber between the electrode and the refractory liner previously mentioned. When power is passed from the negative to the positive electrode liner, the particle-containing plasma stream which passes the negative rod and the positive liner is ionized to form a flame. This forms the plasma stream. This stream then passes to the outside of the jet apparatus. Directly aligned on the outside of the ignition chamber are two additional carbon or tungsten rods, which carry a voltage which creates a flow of electrical current between the two rods. These I shall refer to as my accelerating rods, or accelerating electrodes. Directly in line with the the plasma stream, at and lying /8 inch lower than the accelerating rods, and located on the opposite sides of the accelerating rods, is an electromagnet attached to a yoke which forms a magnetic flux. The plane that includes the center of the electromagnet should cut the plasma about /2 inch above the end of the positive electrode, the axis of the accelerating arc is located about inch higher.

These units in combination form the accelerating assembly for the improved plasma jet unit. This accelerating unit along with a rhe ostat which is in the line supplying power to the accelerating rod completes the necessary apparatus to form the accelerating unit which is my improvement for a plasma jet apparatus.

The object of this invention is to provide a method and apparatus for stabilizing, accelerating, increasing the temperature and efliciency of the plasma jet stream emerging from a plasma jet torch. The term efliciency means higher work performance with additional power development.

Another object of this invention is to provide an accelerating assembly creating a magnetic field by combining a magnetic yoke with an electromagnet and electrodes in a relationship so as to improve the characteristics of. the plasma.

And still another object of this invention is to create a magnetic field located outside the plasma jet chamber so that the accelerating assembly can be added to the present plasma chambers now in industry without making major structural changes in the apparatus.

FIGURE 1 represents the plasma jet unit which includes an arc chamber 1 surrounded by a copper water jacket 3 for cooling the chamber. Below the arc chamber is means 4 for introducing inert gas into the system through a perforated screen 5 with a close-fitting hole through which passes a carbon, graphite or thoriated tungsten electrode 6 attached to a source of electrical power. The upper end of the electrode is circumscribed by a replaceable cylindrical carbon insert 7 also connected to a source of electrical power as shown in FIGURE 2 through which the plasma jet flame passes to the outside. Directly above the exit hole is the accelerating assembly which consists of two electrodes 2 and 8 positioned at exactly 90 to the electromagnet 9' FIGURE 2 at the ends of a yoke 10'. The upper section of the yoke is covered with 815 turns of #14 cotton enamel magnetic wire. The electrodes (2' and 8') FIGURE 2 are each attached to a source of direct current electricity with a variable rheostat 12'. The ends of the magnetic wire around the yoke are connected to another source of electrical power.

FIGURE 2, whichis a schematic drawing of the plasma jet gun, shows the manner in which the electrical source of power is connected to the electrode 6' and to the positive connection 11' near the carbon refractory insert 7' in the throat of the chamber. The upper section, which shall be termed the accelerating assembly, shows the negative electrode 8' with a connection through an on and off switch to a source of direct current electrical power. The plus side of the electrode 2' is connected through a rheostat 12' for varying the intensity of the power being applied. The magnetic Wire around the yoke is connected through a switch to a constant source of direct current.

FIGURE 3 is an enlarged sectional view of the spaced relationship of the electrodes 2' and 8 and electromagnet 9' above the exit port of the plasma jet gun.

The theory upon which the accelerating principle is based depends on two factors: (1) that the plasma particles flowing from the arc chamber are charged moving particles, and (2) that charged particles passing through a magnetic field will be alfected by the magnetic field in combination with the electrodes. The spirit of this invention will operate properly if the electrodes 2 and 8' are arranged at approximately 90 to the electromagnet 9' mounted on the yoke 10'. However, the preferred embodiment of this invention would be to arrange the electrodes 2 and 8 in a spaced parallel relationship 90 to the electromagnet in a parallel plane /a inch above the plane of the electromagnet axis.

This spaced relationship of the electromagnet and the electrodes, or the oifsetting of the electrical field to the magnetic field, enables the molecules of the substance comprising the plasma jet flame to reach a maximum peak of excitement. Further, the spaced relationship of the electromagnet and the electrodes causes increased movement and bombardment of the molecules in the plasma jet flame itself. This results is a jet stream moving at a higher velocity in a more exacting direction with increased temperatures. When the power is applied to the electrodes 2' and 8' and the yoke 10, the magnetic field will then be perpendicular to the stream of the charged plasma. The acceleration rate of the plasma is controlled by adjusting the rheostat which regulates the current being fed to the electrodes at 2' and 8'.

A review of the prior art teaches that stabilizing of the plasma jet is known. However, I have discovered that by adding the disclosed accelerating assembly to the plasma apparatus described herein that not only is the plasma jet stream accelerated and stabilized, but that extremely high temperatures of 20,000 F. or more are obtained and a velocity of 22,400 feet per second is obtained.

Experimentation has shown that supplying voltage of 4075 volts and a current of 150 amperes to the plasma gun alone will produce a discharge of a temperature of 15,000 F. without the accelerating assembly herein described. By adding the accelerating assembly, the temperature is increased to 20,000 P. or more along with stabilization and concentration of the plasma discharge on the object being heated.

To obtain optimum operation of the disclosed accelerating assembly, the following procedure is suggested. The cooling water in the cooling section 3 of the plasma gun should be circulating, the electrode 6 should be brought into position with the carbon insert so that when the power is turned on, there is sufiicient flow of electricity to strike the arc. Inert gas such as hydrogen or helium is fed in at 4 with a pressure slightly in excess of atmospheric pressure. With the plasma jet operating, a magnetic field is introduced directly outside the throat of the plasma gun by passing a current through the yoke 70 10, producing a magnetic flux between poles 9. The plasma discharge has a tendency to bend to one side.

By passing a current through the electrodes 2' and 8' enabling current to pass through the flow of plasma, the discharge is stabilized and the temperature of the discharge greatly increased. The acceleration of the flame is controlled by adjusting the rheostat 12' FIGURE 2. By adjusting the rheostat, the acceleration of the plasma discharge can be increased or decreased. The rate of acceleration also aifects the temperature of the plasma. An increase in acceleration increases the temperature While a decrease in acceleration decreases the temperature.

This new and improved apparatus has proven useful in heating metal structures for tempering. It can be used for drilling holes in the earth structure where extremely high temperatures are required. It is useful in the chemical laboratory in forming compounds containing ceramics and metals which were heretofore impossible to form. Still another utilization of this apparatus requiring a slight modification of the apparatus shown herein, will utilize granular material such as a ceramic refractory or metal which is fed into the plasma stream through the arc chamber, heated and sprayed as a coating material on metal surfaces.

Various embodiments of this invention in addition to what has been illustrated and described can be employed without departing from the scope of the accompanying claims.

I claim:

1. A high temperature plasma generator comprising:

(a) a chamber;

(b) are discharge electrodes mounted in said chamher;

(0) said chamber being provided with inlet means for introducing an ionizable medium therein;

(d) means connecting said discharge electrodes to an electrical circuit providing current thereto capable of generating and maintaining an are;

(e) said chamber being provided with an outlet for the arc discharge gases formed therein constituting the initially formed plasma, said outlet being the discharge nozzle for said plasma;

(f) electrodes positioned in proximity to and outside said chamber transversely of the mouth of the nozzle and spaced so that the plasma will flow between the active surfaces of opposite signs;

(g) an electromagnet the poles of opposite polarity being positioned transversely of the said mouth of the said nozzle and spaced so that the plasma will flow between the said poles;

(h) the said electrodes being positioned approximately to and in a plane substantially parallel to said electromagnet;

(i) means for excitation of the said electromagnet;

(j) and means for excitation of the last-named electrodes providing substantial discharge current thereto for generating a flow of current therebetween.

2. The generator according to claim 1, wherein the said discharge nozzle is provided with an electrical conductive refractory insert, said insert constituting one electrode of the arc discharge electrodes.

3. The generator according to claim 2, wherein the said chamber is surrounded by water cooling means to cool the said chamber.

References Cited UNITED STATES PATENTS 3,005,931 10/1961 Dandl 315-111 3,278,796 10/1966 Takei 315-231 DAVID J. GALVIN, Primary Examiner. STANLEY D. SCI-ILOSSER, Examiner. 

1. A HIGH TEMPERATURE PLASMA GENERATOR COMPRISING: (A) A CHAMBER; (B) ARC DISCHARGE ELECTRODES MOUNTED IN SAID CHAMBER; (C) SAID CHAMBER BEING PROVIDED WITH INLET MEANS FOR INTRODUCING AN IONIZABLE MEDIUM THEREIN; (D) MEANS CONNECTING SAID DISCHARGE ELECTRODES TO AN ELECTRICAL CIRCUIT PROVIDING CURRENT THERETO CAPABLE OF GENERATING AND MAINATINING AN ARC; (E) SAID CHAMBER BEING PROVIDED WITH AN OUTLET FOR THE ARC DISHCARGE GASES FORMED THEREIN CONSTITUTING THE INITIALLY FORMED PLASMA, SAID OUTLET BEING THE DISCHARGE NOZZLE FOR SAID PLASMA; (F) ELECTRODES POSITIONED IN PROXIMITY TO AND OUTSIDE SAID CHAMBER TRANSVERSELY OF THE MOUTH OF THE NOZZLE AND SPACED SO THAT THE PLASMA WILL FLOW BETWEEN THE ACTIVE SURFACES OF OPPOSITE SIGNS; (G) AN ELECTROMAGNET THE POLES OF OPPOSITE POLARITY BEING POSITIONED TRANSVERSELY OF THE SAID MOUTH OF THE SAID NOZZLE AND SPACED SO THAT THE PLASMA WILL FLOW BETWEEN THE SAID POLES; (H) THE SAID ELECTRODES BEING POSITIONED APPROXIMATELY 90* TO AND IN A PLANE SUBSTANTIALLY PARALLEL TO SAID ELECTROMAGNET; (I) MEANS FOR EXCITATION OF THE SAID ELECTROMAGNET; (J) AND MEANS FOR EXCITATION OF THE LAST-NAMED ELECTRODES PROVIDING SUBSTANTIAL DISCHARGE CURRENT THERETO FOR GENERATING A FLOW OF CURRENT THEREBETWEEN. 